Transition Piece Cross Sectional Area Convergence Reduction And Selection

ABSTRACT

Disclosed herein are apparatuses, methods, and systems for cross sectional area convergence reduction and selection. In an embodiment, an aft end cross sectional area is determined for a transition piece and a forward end cross sectional area is determined for the transition piece. The transition piece may be fabricated based on a constant slope of cross sectional area change between the aft end and the forward end.

CROSS REFERENCE TO RELATED APPLICATIONS

The subject matter disclosed in this patent application is related tothe subject matter disclosed and claimed in the following U.S. patentapplication Ser. No. ______, Attorney Docket No. 257648/GEEN0032, andU.S. patent application Ser. No. ______, Attorney Docket No.257646-257650/GEEN0033. Each of the above U.S. patent applications werefiled on even day herewith and are incorporated by reference herein intheir entirety.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to combustionsystems and more specifically hot gas flow.

BACKGROUND

In a typical can annular gas turbine engine, a plurality of combustorsare arranged in a generally annular array about the engine. Thecombustors receive pressurized air from the engine's compressor, addfuel to create a fuel and air mixture, and combust the mixture toproduce hot gases. The hot gases exiting the combustors are utilized toturn a turbine, which is coupled to a shaft that drives a generator forgenerating electricity.

The hot combustion gas is conveyed from the combustor liner to theturbine by a transition piece or duct. The hot combustion gas flowingthrough the transition piece subjects the duct structure to very hightemperatures and can lead to premature deterioration that requiresrepair and replacement of the transition ducts. A significant crack orother deterioration in a single area of an otherwise relativelyundamaged transition piece may have a significant impact on gas turbineperformance and may require replacement of the entire transition piece.

BRIEF DESCRIPTION OF THE INVENTION

Disclosed herein are apparatuses, methods, and systems for transitionpiece cross sectional area convergence reduction and selection. In anembodiment, a method determines an aft end cross sectional area for atransition piece and a forward end cross sectional area for thetransition piece. The transition piece may be fabricated based on aconstant slope of cross sectional area change between the aft end andthe forward end.

In an embodiment, a system has a first processor and a first memory. Thefirst memory may be communicatively coupled to the first processor saidfirst memory having stored therein computer-readable instructions that,if executed by the first processor, cause the processor to performoperations comprising determining an aft end cross sectional area for atransition piece; determining a forward end cross sectional area basedon the aft end cross sectional area for the transition piece;determining the constant slope of cross sectional area change betweenthe aft end and the forward end; and fabricating the transition piecebased on the constant slope of cross sectional area.

In an embodiment, a transition piece comprises a cross sectional areaalong the length of the transition piece that stays within +/−3% of aconstant slope cross section area, wherein the constant slope crosssectional area is based on an aft end cross sectional area measurementand a corresponding forward end cross sectional area measurement at arespective length.

This Brief Description of the Invention is provided to introduce aselection of concepts in a simplified form that are further describedbelow in the Detailed Description. This Brief Description of theInvention is not intended to identify key features or essential featuresof the claimed subject matter, nor is it intended to be used to limitthe scope of the claimed subject matter. Furthermore, the claimedsubject matter is not limited to limitations that solve any or alldisadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 is an exemplary illustration of a transition piece;

FIG. 2 is an exemplary illustration of a transition piece;

FIG. 3 an exemplary graph that illustrates the change of the crosssectional areas of transition pieces from aft to forward end;

FIG. 4 illustrates a non-limiting, exemplary method of implementingtransition piece cross sectional area convergence as disclosed herein;and

FIG. 5 is an exemplary block diagram representing a general purposecomputer system in which aspects of the methods and systems disclosedherein thereof may be incorporated.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an exemplary illustration of a transition piece 100.Transition piece 100 has a forward (inlet) end 105 and an aft (outlet)end 110. Hot gases flow into inlet 105 and flow through the length oftransition piece 100. The hot gases exit transition piece 100 at outlet110.

It has been shown that the life limiting area of a transition pieceoften has higher temperatures placed on it than other areas of thetransition piece. These higher temperatures may cause a higher strainrange for every start to stop cycle of the turbine. Over time, thesestrain cycles may accumulate and become the transition piece's lifelimit. These higher temperatures may also cause oxidation of thetransition piece material. Over time, this oxidation may accumulate andbecome the transition piece's life limit. As stated herein, regardlessof the relatively undamaged nature of the other portions of thetransition piece, the entire transition piece is replaced whensignificant damage (e.g., cracking) is done to a particular area of thetransition piece.

There are certain respective cross sectional areas of a transition pieceat the forward (fwd) and aft end. Traditionally, as a rule of thumb, theforward end cross sectional area of a transition piece is 15% largerthan the outlet (i.e., aft end) of the transition piece. The 15% rule ofthumb is used for transition pieces in order to reduce recirculation inthe transition piece. FIG. 2 is an exemplary illustration of atransition piece 200. An inlet cross sectional area may be taken at 205and an outlet cross sectional area may be taken at 210. Traditionallythe percentage decrease of the inlet cross sectional area at 205compared to the outlet cross sectional area at 210 would conform to the15% rule of thumb. Traditionally the middle section 215 has a crosssectional area that diverges substantially before reaching the final 15%rule of thumb percentage.

Analysis has shown that hot spots are created within a transition piecebecause areas may diverge within the middle section of the transitionpiece and cause recirculation zones. As disclosed herein, reduction of atransition piece cross sectional area from forward end to aft end in aconstant rather than divergent manner may substantially reduce hotspots. In an embodiment, reducing that amount of cross sectional areaconvergence from the 15% rule of thumb (e.g., the aft having a crosssectional area that is 6% less than the fwd) and/or maintaining within atolerance range of at most +/−3% may increase the life of a transitionpiece.

FIG. 3 is an exemplary graph that illustrates the change of the crosssectional areas of transition pieces from aft to forward end. Axis y 302denotes the cross sectional area of a transition piece and axis x 303denotes the length of the transition piece from aft end to fwd end. Line305 is a line that has a constant slope, wherein the cross sectionalarea changes constantly along the length from aft to forward end. Theideal or reference line 305 (hereinafter reference line) may bedetermined using standard algebraic equations and the like once the aftand fwd end cross sectional area and length are determined Curve 310 isa curve that is out of the discussed +/−3% range along the length of thetransition piece. For example, point 311 shows that the transition piecerepresented by curve 310 has an approximate cross sectional area of 208at length 15, while the transition piece represented by reference line305 has an approximate cross sectional area of 188 at length 15. Usingthe aforementioned measurements point, 311 of curve 310 diverges byapproximately 10 percent at the same length of the reference line 305.

Curve 315 is a curve that is within the discussed +/−3% range along thelength of the transition piece. For example, point 316 shows that thetransition piece represented by curve 315 has an approximate crosssectional area of 192 at length 15, while the transition piecerepresented by line 305 has an approximate cross sectional area of 188at length 15. Using the aforementioned measurements, point 316 divergesby approximately 2.1% from the reference line 305.

A computer generated or physical manifestation of a transition piece maybe created based on a predetermined calculated constant change crosssectional area reference line. An example of a physical manifestationmay be a physical transition piece mold that conforms to the referenceline with +/−3% divergence in cross sectional area. Measurements ofcross sectional area may be taken at every 1/10 interval of the lengthof the entire transition piece. More frequent measurements may be takenfor more data points and better results when creating a transitionpiece.

FIG. 4 illustrates a non-limiting, exemplary method of implementingtransition piece cross sectional area convergence as disclosed herein.Method 400 may be performed by computing equipment including mobiledevices (e.g., tablet computers), servers, or any other device that canexecute computing functions.

In an embodiment at block 405, a transition piece aft shape and endcross sectional area may be determined. The aft end cross sectional areadetermination may be based on characteristics of a corresponding stageone nozzle (S1N). At block 410 the transition piece fwd end shape andcross sectional area may be determined. The fwd end cross sectional areamay be based on the aft end cross sectional area. At block 415, theconstant slope of cross sectional area change along the length of thetransition piece between aft end and fwd end may be determined. At block420, a transition piece may be created based on the constant slope ofthe cross sectional area and remaining within a +/−3% tolerance level.

Experiments have shown that if care is taken to make sure the crosssectional area is within +/−3% of a constant change cross sectional areareference line, then hot spots may be reduced and the life of thetransition piece may be extended. Although a 15% rule of thumb isdiscussed herein for cross sectional area change of aft and fwd ends,other percentages may be appropriate. Experiments have shown that the15% rule of thumb can be lowered (for example to 5%) with better resultsin transition piece life when the divergence of the cross sectional areaalong the length of the transition piece is within +/−3%. The closer thedivergence of the cross sectional area is to 0% there may be less needto reduce the cross sectional area from the fwd to aft end and the 15%rule of thumb percentage may trend to 0% while giving superior results.

The technical effect of the method is the fabrication of a physicalmanifestation (e.g., metal) of a transition piece or the creation of acomputer generated representation of a transition piece in a turbinesystem. Tests of the transition piece may be done using physicaltransition pieces with test equipment, computer specifications of atransition piece and corresponding computer analysis, or the like. Testsmay be done on a particular transition piece design, such as atransition piece made for one or more generator models, and implementedin a physical form or digital form. Although measurements are describedas being taken at the forward and aft end, it is reasonable to takemeasurements within an approximate area of either end.

FIG. 5 and the following discussion are intended to provide a briefgeneral description of a suitable computing environment in which themethods and systems disclosed herein and/or portions thereof may beimplemented. Although not required, the methods and systems disclosedherein may be described in the general context of computer-executableinstructions, such as program modules, being executed by a computer,such as a client workstation, server or personal computer. Generally,program modules include routines, programs, objects, components, datastructures and the like that perform particular tasks or implementparticular abstract data types. Moreover, it should be appreciated thatthe methods and systems disclosed herein and/or portions thereof may bepracticed with other computer system configurations, including hand-helddevices, multi-processor systems, microprocessor-based or programmableconsumer electronics, network PCs, minicomputers, mainframe computersand the like. The methods and systems disclosed herein may also bepracticed in distributed computing environments where tasks areperformed by remote processing devices that are linked through acommunications network. In a distributed computing environment, programmodules may be located in both local and remote memory storage devices.

FIG. 5 is a block diagram representing a general purpose computer systemin which aspects of the methods and systems disclosed herein and/orportions thereof may be incorporated. As shown, the exemplary generalpurpose computing system includes a computer 520 or the like, includinga processing unit 521, a system memory 522, and a system bus 523 thatcouples various system components including the system memory to theprocessing unit 521. The system bus 523 may be any of several types ofbus structures including a memory bus or memory controller, a peripheralbus, and a local bus using any of a variety of bus architectures. Thesystem memory includes read-only memory (ROM) 524 and random accessmemory (RAM) 525. A basic input/output system 526 (BIOS), containing thebasic routines that help to transfer information between elements withinthe computer 520, such as during start-up, is stored in ROM 524.

The computer 520 may further include a hard disk drive 527 for readingfrom and writing to a hard disk (not shown), a magnetic disk drive 528for reading from or writing to a removable magnetic disk 529, and anoptical disk drive 530 for reading from or writing to a removableoptical disk 531 such as a CD-ROM or other optical media. The hard diskdrive 527, magnetic disk drive 528, and optical disk drive 530 areconnected to the system bus 523 by a hard disk drive interface 532, amagnetic disk drive interface 533, and an optical drive interface 534,respectively. The drives and their associated computer-readable mediaprovide non-volatile storage of computer readable instructions, datastructures, program modules and other data for the computer 520.

Although the exemplary environment described herein employs a hard disk,a removable magnetic disk 529, and a removable optical disk 531, itshould be appreciated that other types of computer readable media whichcan store data that is accessible by a computer may also be used in theexemplary operating environment. Such other types of media include, butare not limited to, a magnetic cassette, a flash memory card, a digitalvideo or versatile disk, a Bernoulli cartridge, a random access memory(RAM), a read-only memory (ROM), and the like.

A number of program modules may be stored on the hard disk, magneticdisk 529, optical disk 531, ROM 524 or RAM 525, including an operatingsystem 535, one or more application programs 536, other program modules537 and program data 538. A user may enter commands and information intothe computer 520 through input devices such as a keyboard 540 andpointing device 542. Other input devices (not shown) may include amicrophone, joystick, game pad, satellite disk, scanner, or the like.These and other input devices are often connected to the processing unit521 through a serial port interface 546 that is coupled to the systembus, but may be connected by other interfaces, such as a parallel port,game port, or universal serial bus (USB). A monitor 547 or other type ofdisplay device is also connected to the system bus 523 via an interface,such as a video adapter 548. In addition to the monitor 547, a computermay include other peripheral output devices (not shown), such asspeakers and printers. The exemplary system of FIG. 5 also includes ahost adapter 555, a Small Computer System Interface (SCSI) bus 556, andan external storage device 562 connected to the SCSI bus 556.

The computer 520 may operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computer549. The remote computer 549 may be a personal computer, a server, arouter, a network PC, a peer device or other common network node, andmay include many or all of the elements described above relative to thecomputer 520, although only a memory storage device 550 has beenillustrated in FIG. 5. The logical connections depicted in FIG. 5include a local area network (LAN) 551 and a wide area network (WAN)552. Such networking environments are commonplace in offices,enterprise-wide computer networks, intranets, and the Internet.

When used in a LAN networking environment, the computer 520 is connectedto the LAN 551 through a network interface or adapter 553. When used ina WAN networking environment, the computer 520 may include a modem 554or other means for establishing communications over the wide areanetwork 552, such as the Internet. The modem 554, which may be internalor external, is connected to the system bus 523 via the serial portinterface 546. In a networked environment, program modules depictedrelative to the computer 520, or portions thereof, may be stored in theremote memory storage device. It will be appreciated that the networkconnections shown are exemplary and other means of establishing acommunications link between the computers may be used.

Computer 520 may include a variety of computer readable storage media.Computer readable storage media can be any available media that can beaccessed by computer 520 and includes both volatile and nonvolatilemedia, removable and non-removable media. By way of example, and notlimitation, computer readable media may comprise computer storage mediaand communication media. Computer storage media include both volatileand nonvolatile, removable and non-removable media implemented in anymethod or technology for storage of information such as computerreadable instructions, data structures, program modules or other data.Computer storage media include, but are not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can be accessed by computer 520. Combinations of any of theabove should also be included within the scope of computer readablemedia that may be used to store source code for implementing the methodsand systems described herein. Any combination of the features orelements disclosed herein may be used in one or more embodiments.

In describing preferred embodiments of the subject matter of the presentdisclosure, as illustrated in the Figures, specific terminology isemployed for the sake of clarity. The claimed subject matter, however,is not intended to be limited to the specific terminology so selected,and it is to be understood that each specific element includes alltechnical equivalents that operate in a similar manner to accomplish asimilar purpose.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed:
 1. A method comprising: determining an aft end crosssectional area for a transition piece; determining a forward end crosssectional area for the transition piece; and fabricating the transitionpiece based on a constant slope of cross sectional area change betweenthe aft end and the forward end.
 2. The method of claim 1, wherein thetransition piece is within +/−3% of the constant slope of crosssectional area along the length of the transition piece.
 3. The methodof claim 1, wherein the transition piece is within an average +/−3% ofthe constant slope of cross sectional area along the length of thetransition piece.
 4. The method of claim 1, wherein the fabricatedtransition piece is within +/−3% of the constant slope of crosssectional area.
 5. The method of claim 1, wherein the forward end crosssectional area is taken near the attachment point of the combustor linerand the transition piece.
 6. The method of claim 1, wherein the forwardend cross sectional area is based on the aft end cross sectional area.7. The method of claim 1, wherein the aft end cross sectional area istaken near the aft frame.
 8. A transition piece comprising a crosssectional area along the length of the transition piece that stayswithin +/−3% of a constant slope cross sectional area, wherein theconstant slope cross sectional area is based on an aft end crosssectional area measurement and a corresponding forward end crosssectional area measurement at a respective length.
 9. The transitionpiece of claim 8, wherein the transition piece is within +/−3% of theconstant slope of cross sectional area along the length of thetransition piece.
 10. The transition piece of claim 8, wherein thetransition piece is within an average +/−3% of the constant slope ofcross sectional area along the length of the transition piece.
 11. Thetransition piece of claim 8, wherein the fabricated transition piece iswithin +/−3% of the constant slope of cross sectional area at everyone-tenth interval of the length of the transition piece.
 12. Thetransition piece of claim 8, wherein the forward end cross sectionalarea is taken near the attachment point of the combustor liner and thetransition piece.
 13. The transition piece of claim 8, wherein the aftend cross sectional area is taken near the attachment point of the aftframe and a stage one nozzle.
 14. The transition piece of claim 8,wherein the aft end cross sectional area is taken near the aft frame.15. A system comprising: a first processor adapted to executecomputer-readable instructions; and a first memory communicativelycoupled to said first processor, said first memory having stored thereincomputer-readable instructions that, if executed by the first processor,cause the processor to perform operations comprising: determining an aftend cross sectional area for a transition piece; determining a forwardend cross sectional area based on the aft end cross sectional area forthe transition piece; determining the constant slope of cross sectionalarea change between the aft end and the forward end; and creating thetransition piece based on the constant slope of cross sectional area.16. The system of claim 15, wherein the transition piece is within +/−3%of the constant slope of cross sectional area along the length of thetransition piece.
 17. The system of claim 15, wherein the transitionpiece is within an average +/−3% of the constant slope of crosssectional area along the length of the transition piece.
 18. The systemof claim 15, wherein the forward end cross sectional area is taken nearthe attachment point of the combustor liner and the transition piece.19. The system of claim 15, wherein the aft end cross sectional area istaken near the aft frame.
 20. The system of claim 15, whereincomputer-readable instructions include taking a cross sectional areameasurement of the transition piece at every one-tenth interval of thelength of the transition piece.